DOUBLE STARS : DISTANCES OF STARS 79 



lessons to his pupils per week ; groaning and fretting 

 under the incapacity of not a few of them a man who 

 had to be in his place conducting a band or a concert, 

 and supervising a church's music, or who, instead of 

 seeking rest in sleep, when the day's weary work 

 was done, would often spend the night in observing 

 the stars. His sister, who was his invariable com- 

 panion in these night watches, had ample reason to 

 say of him, " He did in one season more than anyone 

 else could have done, and would have resumed the 

 hunt [for Saturn's satellites] the next fifteen years, if 

 nothing had interfered." 



The new path on which he entered, and which led 

 him into other and most attractive fields of inquiry, 

 was the distance of what are called the fixed stars 

 from the solar system. He knew that at the distance 

 of the nearest of them, twice the sun's distance from 

 the earth, immense though it seems, appears no bigger 

 than a needle point, and cannot be used as a base line 

 for measurement, or, indeed, as a line at all. He gave 

 up the thought of attempting to solve the problem 

 from that, the most natural and the easiest side. It 

 was good for neighbours so near us as Mars and Venus. 

 It was useless for Sirius or Arcturus. Following, 

 perhaps, the example of Galileo, he believed that 

 observations on stars so close together that neither 

 the naked eye nor ordinary telescopes could separate 

 them, and make two out of one, would lead to a 

 discovery of their distance. He did not succeed in his 

 purpose, but he was " introduced to a new series of 

 observations and discoveries." He resolved to examine 

 every star in the heavens with the utmost attention 

 and a very high power, that he might collect such 



